The goal of this proposal is to better understand the role of the song control system in the perception of conspecific song in adult songbirds. Songbirds must not only learn to produce songs, but also learn to recognize conspecific individuals based on auditory communication. Previous research has established that lesions to areas within the song control system alter a bird's ability to make discriminations between familiar songs. Also, molecular techniques have been used to correlate auditory experience with protein phosphorylation within neurons of the song control system. The proposed experiments will investigate both the mechanisms and structures necessary for songbirds to process auditory information and form long term memories. Three hypotheses will be tested: (1) the phosphorylation of CREB is necessary in the formation of new auditory memories, (2) the anterior forebrain pathway is necessary for the recognition of familiar songs, and (3) the neostriatal nucleus HVc is necessary for the perception of conspecific song. I will test hypotheses (1) and (2) in wild song sparrows by simulating social interactions that the birds have when defending their territories during the breeding season. Hypothesis (3) will be tested with canaries in the laboratory using an operant conditioning task. These studies will increase our knowledge of the way in which songbirds perceive and learn to recognize the songs of conspecifics.